1. Field of the Invention
The present invention relates to improved organosilicon compositions which are prepared from hydroxylated diorganopolysiloxane polymers, organosilicon resins, alkoxylated organosilicon compounds, and organic derivatives of titanium. These compositions are storage-stable in the absence of moisture and are quickly curing into elastomers when they are exposed to normal ambient atmosphere. Furthermore, within the course of their transformation into elastomers they strongly adhere to the materials onto which they have been spread.
2. Description of the Invention
Curable oganosilicon compositions are known to the art which are curable into solid elastic materials at room temperature in the presence of moisture, whereby these materials adhere to the support which has been contacted with said compositions, without previously depositing thereon an adhesion primer. In particular, such compositions are disclosed in the French Pat. Nos. 2,074,144 and 2,076,539 and in the U.S. Pat. No. 3,686,357. The adherent properties of the compositions which are disclosed in these cited patents have been achieved by introduction therein of certain aminoalkylated oganosilicon compounds. Yet this introduction renders the storage-stability of such compositions rather poor and unpredictable. Because of this it is nearly impossible to provide the trade with a ready-to-use composition which consists of but a single component. Compositions which exhibit a better stability are also known and, more particularly, are disclosed in the published French Patent Applications No. 2,142,050, No. 2,251,602 and U.S. Pats. No. 3,922,246 and No. 3,965,280. The compositions according to the French Application No. 2,142,050 are formulated by mixing hydroxylated diorganopolysiloxane polymers, alkylated silanes, titanium chelates and adhesion improving agents, these latter agents being silylated isocyanurates. Yet by introduction of these isocyanurates, no rapid vulcanization times at ambient temperature can be achieved, e.g., periods of less than 2 hours at the surface and less than 18 hours throughout the mass.
In order to achieve rapid vulcanization which is a goal of most elastomer users (to obviate the need for storing large numbers of materials treated with such compositions) accelerators have to be introduced. The French Application No. 2,142,050 thus uses metal derivatives, preferably organic tin derivatives, for this purpose. Since these derivatives have the disadvantage of being toxic and polluting, their presence is desirably avoided, especially in such fields of application where the elastomers come into contact with foods, cosmetic products, pharmaceutical products or the human body.
The compositions which are described in the French Application No. 2,251,602 are quite similar to those of the Application No. 2,142,050; nevertheless, they differ from same in the per weight ratio between the titanium chelates and the alkylated silanes, which is at least 1, whereas it is less than 1 in the Application No. 2,142,050. This particular feature allows one to obtain elastomers having a low modulus. Nonetheless, other than the modulus distinction, the same disadvantages which characterize the compositions of the Application No. 2,142,050 characterize those of the '602 Application as well. Indeed, it has even been shown through experimentation that it is desirable to add to the '602 type compositions, the aforementioned class of silylated isocyanurate adhesion improving agent. Furthermore, these compositions only give rise to elastomers having low modulus, thus preempting the possibility of obtaining elastomers which, e.g., exhibit high hardness and have high tensile strength.
The compositions according to the commonly assigned U.S. Pat. Nos. 3,922,246 and 3,965,280, are obtained by mixing hydroxylated diorganopolysiloxane polymers, organosilicon resins consisting of triorganosiloxyl and siloxyl units, alkoxylated oganosilicon compounds and organic titanium derivatives. In addition to their ability of being converted into self-adhesive elastomers, such adhesive properties being attained without use of complex additives as, e.g., the silylated isocyanurates, same can be converted into elastomers whose mechanical properties vary over a wide range of values. Same also require relatively short curing periods. Nevertheless, it is a desideratum that such curing times be further reduced independently of desired mechanical and adhesive properties.